3io Scheme of Water Supply. [J illy, 
T he well at Thames Head, pumping from the Great Oolite 
near Cirencester, gave x6 grains per gallon ;* and the waters 
of the Chelt, above Charlton Mill, near Cheltenham, which 
rise from springs at the base of the Inferior Oolite, gave 
20 grains per gallon, of which 4 grains consisted of 
organic matter.* 
Marlstone, or Middle Lias . 
I have no analysis of water from this formation ; but, 
judging by the appearance of the numerous springs which 
issue forth from the flanks of the hills of Marlstone in the 
Midland Counties, it may be considered of good quality 
and moderately soft. In a formation so variable as the 
Marlstone — consisting in some places of calcareous sand- 
stones, in others of ferruginous limestones passing into iron- 
stone — the character of the water must be liable to consider- 
able variation in different localities. 
New Red Sandstone. 
Next to the Chalk, the New Red Sandstone-— including the 
Bunter and Lower Keuper divisions — is the most important 
water-bearing formation in the district under consideration, 
and the waterwhich ityieldspossessesthis advantage overthat 
of the Chalk, that it is softer, and generally capable of being 
used for all domestic and manufacturing purposes. From 
the numerous analyses that have been made of these waters 
in different localities in the central and N.W. counties, we 
have the means of arriving at general conclusions on this 
subject, and for special and accurate details we may look 
forward with interest to the Reports of the Committee on 
Underground Waters, appointed by the British Association 
in 1874. t The beds of the Bunter Sandstone are wonder- 
fully adapted both to aCt as natural filters and as reservoirs 
for that portion of the rain which sinks below the surface. 
This may be assumed at one-third of the aCtual rainfall as 
an average ; while in some districts- — where the formation 
consists of soft sandstone or unconsolidated conglomerate, 
devoid of a thick covering of drift clay— -the amount of ab- 
sorption must reach well nigh one-half the amount of rain- 
fall. Owing, also, to its uniformity in composition, and the 
absence of beds of clay or marl of any importance, the 
whole mass of rock below a certain level, and throughout a 
depth of several hundred feet in some districts, becomes 
* Horsley’s Analysis, sup. cit., p. 309. 
f Belfast Meeting. First Report presented at Bristol, 1875. 
